1. Field of the Invention
The present invention generally relates to backlight modules, such backlight modules typically being incorporated into devices such as liquid crystal displays.
2. Discussion of the Related Art
Most liquid crystal display (LCD) devices are passive devices in which images are displayed by controlling an amount of light inputted from an external light source. Thus, a separate light source (for example, backlight module) is generally employed to illuminate an LCD panel of the LCD device.
Referring to FIG. 1, a typical backlight module 10 is shown. The backlight module 10 includes a prism sheet 11, a first diffusion sheet 12, a second diffusion sheet 13, and a light source 15. The prism sheet 11 includes a light incident surface 111 and a light emitting surface 112 opposite to the light incident surface 111. A plurality of elongated V-shaped grooves (not labeled) extend out of the light emitting surface 112 regularly in a direction and parallel to each other. The prism sheet 11 is located between the first diffusion sheet 12 and the second diffusion sheet 13, with the light emitting surface 112 adjacent to the first diffusion sheet 12, and the light incident surface 111 adjacent to the second diffusion sheet 13. The light source 15 is located adjacent to the second diffusion sheet 13. When light rays from the light source 15 are emitted into the prism sheet 11 after being scattered from the second diffusion sheet 13, the light rays are refracted at/by the prism sheet 11 and emitted into the first diffusion sheet 12. The light rays are scattered from the first diffusion sheet 12 and finally emitted into an LCD panel (not shown) disposed on the first diffusion sheet 12.
In order to improve optical uniformity, a diffusion plate 14 is further provided. The diffusion plate 14 is located between the second diffusion sheet 13 and the light source 15. Referring to FIG. 2, the diffusion plate 14 includes a transparent main body 141 and a plurality of dispersion particles 142 dispersed in the main body 141. The dispersion particles 142 are configured for dispersing the light rays. When the light rays are emitted into the diffusion plate 14, the light rays are further scattered by the dispersion particles 142 again and again.
However, the backlight module 10 is Newton ring interference action-prone because the V-shaped grooves extend out of the light emitting surface 112 regularly in a direction, thus, decreasing the optical uniformity of the backlight module 10.
Therefore, a new backlight module is desired in order to overcome the above-described shortcomings.